Apparatus for use in the treatment of oil, gas, and gas-condensate wells



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CMAN @A TG M AL PT. PO A March 1l, 1952 INVENToR /l'nv CHA /PYES /l/f/VETH f/L E@ T5 Patented Mar. 11, 1952 APPARATUS FOR USE IN THE TREATMENT F OIL, WELLS GAS, AND GAS-CONDENSATE Charles Kenneth Eilerts, Bartlesville, Okla., assignor to the United States ot America. as represented by the Secretary of the Interior Applicatin May 14, 1947. Serial N0. 747,990

' 2 Claims. (Cl. 16S-14) (Granted under the act oi March 3, 1883. as amended April 30, 1928; 370 0. G; 757) The invention described herein may be manufactured and used by or for the Government of the United States for governmental purposes without the payment to me of any royalty thereon in accordance with the provisions of the act of April 30, 1928 (Ch. 460, 45 Stat. L. 467).

This invention relates to the treatmentof wells, it particularly relates to apparatus for the introduction of reagents into the flow string of wells and maintaining well productivity during treatment. p

The equipment at a normally completed well for the recovery of fluid hydrocarbons may be thought of as comprising a casing, a christmas tree, and tubing; The casing is a steel cylinder extending from the surface to the producing zone and serving, among other purposes, to keep the earth from caving and iilling the borehole. The christmas tree is an assembly of pipe fittings attached to the casing at the surface and used for controlling the production from the well. The tubing is a steel cylinder, of a smaller diameter than the casing, attached to the christmas tree and suspended inside the casing.

In these normally completed wells the tubing usually reaches to about the same depth as the casing and generally serves as an eductor of the fluid owing from the well. The annular space between the tubing and the casing is substantially unobstructed, and at the surface, liquid may be injected into the annular space through the casing head and permitted to fall to the bottom of the well. Then it can enter the tubing inlet and now to the surface with the well lluid being produced.

It may be necessary to inject reagents into the wells for various reasons such as corrosion control reagents, emulsion breaking reagents, acidizing reagents, and the like. The injected liquid, for example, an inhibitor, can thus distribute itself over the inner wall of the full length tubing and thus protect the steel surfaces so contacted against corrosion. The tubing of wells completed with the annular space substantially unobstructed can be treated readily with such reagents by injecting the reagent into the casing head so that it falls to the tubing inlet through the annular space between the casing and tubing.

Recent practice, particularly in wells drilled in a gas-condensate iield, has been to complete the well so that uid can be withdrawn through separate eductor tubes from any one of a plurality of producing zones which are at different depths. Wells for recovering fluids from two zones are known as dual completions; and those for re-` covering from three zones are termed triple completions. In such plural completion wells, devices known as packers are used in the annular spaces between the concentric ducts through which the hydrocarbonsm can be produced. Figure l is an elevation, partly in section, of a christmas tree of a typical plural completion Well to which one embodiment of my novel attachment is operatively connected. l

Figure 2 is an enlarged partial section of the attachment illustrated in Figure 1.

Figure 3 is an enlarged section of a preferred modicationof my attachment.

In Figurel, .there is shown a christmas tree assembly I0 ,having a flanged conduit to which a well head magazine II is coaxially secured by a companion flange I2 of the magazine. The christmas tree includes a tubing head valve I3, a production'lianged cross I4, a tubing wing valve I5, a master tubing valve I6, a tubing head Il, a plurality of casing wing valves I8, a flange I 9 Welded to the upper end of an inner casing 20, a plurality of basing head valves 2 I, a casing head 22 for an outer casing 23, an intermediate casing 24, and an inner tube 25.

When it becomes necessary to treat the inner surfaces of the tubing, several problems are imposed. Of especial importance` are: the

annular space between the casing, 20 and the inch. Heretofore, two methods have been employed in attempts to overcome these difficulties. One involves the complete stopping of well production by closing the tubing with an imperforated choke below the level Where treatment is desired, effecting the treatment, and then removing the imperforate choke in order to resume production.

Another current process for `Well treating in-` volves running a small bore tube known as macaroni tubing inside the tubing string to the desired level and pumping the treating re-` agent through the macaroni tubing. This method greatly interferes with well production since it greatly reduces the cross sectional area of the tubing flow string. Further disadvantages include the great diiiculty of inserting the macaroni tubing against well pressures, and the macaroni tubing frequently parts near the surface because of the relatively great weight.

of the long length of macaroni tubing which must be employed. Both methods have the further disadvantages of being applicable only to fluid reagents; ,and these methods have been found to be generally expensive and uneconomical.

Accordingly, it is an object of this invention to provide apparatus for the introduction of reagents for the treating of the inner tubing walls and the bottom hole equipment and Yarea .in Wells that have packers that prevent the introduction of reagents through the annular spaces surrounding the tubing and leading to the bottom hole or producing zone. It is a further object that such apparatus be adaptable to the introduction of solid, liquid and gaseous reagents. It is still another object that in employing such apparatus the well production will not be seriously interfered with. Other `objects and .advantages Will be obvious or will appearhereinafter in the description and the Adrawings exemplifying the invention.

Theseobjects and advantages are accomplished vin accordance with this invention by the method for introducing a reagent into the flow string of -a well while recovering uid hydrocarbons which-comprises conning said reagent in a well headmagazine assembly coaxially superimposed and secured vabove a closed tubing head valve and iiow string; said magazine assembly comprising a tubular body section the lower end of which is adapted to secure said magazine .body section coaxially over the inlet of the tubing head valve, a pressure controlling means for ,said magazine body section, and a lremovable pressure conning means fitted at the upper inlet of said magazine lbody section ;Y thereafter equalizing the pressure between the magazine assembly without releasing the confined reagent, and then releasing said connedreagent into the ilow string.

Referring to Figure 2, there is shown, in section, a novel well head magazine assembly comprising a fluid regulating valve 3i, a screw operated charge supporting and releasing mechanism 32,73, looped suspending means .33 for a charge of reagent 34, a splitcoupling 35, .a clamping rubber sleeve 36 for a tubular guide 3l for guiding the charge of reagent 3ft during the initial portion .ofthe fall of thecharge.

.Referring .to Figure 3, there .is shown, partly in section, another well head magazine assembly 40, comprising a high pressure plug-cock lli, having an inlet |52 and a protruding squared end 43 anda magazine body 44. Fluid under pressure is admitted -to the magazine 44 through a 'pipe 45, a ycontrol valve 46 and a vport `il in the valve casing below the plug of the plug-cock 4|.- A pressure gage 48 is operatively connectedwith the pipe 45 and serves to indicate by the iiuctuations in pressure the progress of a charge i9 fro the magazine body 4A. Y

The. equipment exemplified in all figures of the drawings is to -beunderstood as being such that it can safely withstand the pressures encountered in well operation. Y

The well head magazines as shown in Figures 2 and 3 are readily adapted for the introduction of solid, liquid, or gaseous reagents into the flow string of'wells. When liquid Aor gaseous reagents are introduced, it is preferable to confine the reagent in a frangible container `of such shape and size that it can enter and pass through the flow string and constructed of a material which Will dissolve in the well fluids, the reagent, or blends thereof. l'This method is also applicable for the introduction of solid reagents, powders or finely divided crystalline forms, if the reagent is such that relatively dense, compact lumps, crystals,.\or other solid shapes-cannot beobtained.

In operation of the wellhead magazine shown in Figure 2, the magazine body section 201, with the lower half of the unibolt coupling 204 attached is securedto a closed full-opening tubing head valve (|02 of Figure l) so that it is mounted in a vertical position above the christmas tree and is concentric with the axis of the tubing. The guide cylinder 206, containing the sticks of vreagent or the reagent in frangible containers bound together by cord, is inserted in the body .section .201, and when the suspending means `203 has been attached to the releasing mechanism 202, the coupling 204 is closed.

. Thereafter, :the-.tubinghead valve (|02 of Figure l) is :opened and `the pressure of the charged magazine and the flow string equalized. Referring again to .Figure 2, the reagent .is ythen released .by screwing the threaded vstem .of therestraining and releasing means 202 outward to disengage it from the suspending means .203 thereby lpermitting the reagent to fall and enter the tubing (,I I9 of .Figure 1.).

At times it is desired to retard the fall ofthe reagent during the initial period of fall or until it has entered the tubing. This can be accomplished by opening the pressure regulating valve 20| of Figure 2 before the reagent is released and thereby permitting a greaterquantity ofY `gas to flow up through the guiding means 206 and past the reagent. A rubber sleeve 205 seals the guiding means 206 within the magazine body section 201|- so that for gas to fill vthe space inthe guiding means occupied by the reagent it must ilow up past the reagent. This .upward Vflow of gas tends to retard the initial rate of fall of the reagent.

When magazines of the type exempliiiedfby Figure 3 are employed the operation is greatly simplified. The magazines can be left on the christmas tree at all times and the charging of the magazine is greatly simplified. In opera-- tion of .the well head magazine of the `type shown in `Figure 3, the entire magazine assembly-is secured coaxially above the closed Vtubing head valve. .To charge the plug 302 is opened by opera'ting v.the `valve vstern ,30.3 and .the reagent-- preferably in the fcrm Lof. lumps, sticks, jor cylindrical frangible `containers is 'then introduced through theinlet 30|.. Thereafter., the plug 302 is .closed by Lmeans of valve stem 3.03. Then with the pressure `regulating 'valve 306 in thev -closed position, the tubing head valve iscracked slightly to permit the pressure to .eq-ualizebetween the tubing flow .string and the magazine body chamber304. Thereafter, the tubing headv valve is opened completely to permit 4the reagent to enter the flow string. :The initial rate ,offall ofthe reagent can `be controlled as in the other magazines by permitting the Well fluids to flow rapidly past the falling reagent. This can be accomplished by opening the pressure regulating valve 306 prior to releasing the vreagent by.

or otherarea particularly `desired to be'treated'.

This construction `will stop 4the .fall of thereagent and permit it to blend with the fluids flowing upward through the tubing thereby treating the tubing surfaces. Referring to Figure 1 there is shown as |22 a choke which can be set in the tubing at only desired level and which satisfactorily accomplishes this function of arresting the reagent and permitting the well fluids to pass upward through the tubing iiow string.

By this invention it has been possible to introduce a reagent in the form of cast sticks of sodium chromate about 8 inches long and 1%, inches in diameter and weighing about 0.6 pound, into gas condensate wells producing fluids at a maximum mean iiuid velocity of about 20 feet per second.

The shape of the reagent particle, its density, the density of the flowing iiuid, and the diameter of the tubing are considered important factors limiting the iiuid iiow rate against which reagents can be introduced into the ow string. When it is found that the mean uid velocity of the well iiuids is too great to permit the introduction of the selected reagent it is possible to reduce the well iiuid iiow rate While the reagent is being introduced Without greatly affecting the total well production. This can be accomplished by throttling down on the tubing wing valve prior to opening the tubing head valve and releasing the reagent.

An article by the inventor entitled Sodium Chromate Eifective in Combating Corrosion in Gas Wells in the Oil and Gas Journal of May 18, 1946 (page 124) describes some early testing of a well head magazine as a means for introducing reagents.

As shown in the foregoing description and drawings, an apparatus for introducing reagents into wells Without appreciably diminishing well production has been provided.

Since many Widely differing embodiments of the invention will occur to one skilled in the art, the invention is not limited to the specific details illustrated and described, and various changes can be made therein without departing from the spirit and scope thereof.

What is claimed is:

1. In a producing well having an assembly of equipment including a christmas tree for maintaining the well under pressure, a tubular conduit extending into the well and above the casing Vhead and having a ow controlling valve intermediate its length and positioned above the casing head, a device secured to the upper end of the tubular conduit for the introduction'of reagents into the well, While maintaining well production during treatment, said device comprising a connecting section of tubing which forms a charging magazine for a reagent secured to the upper end of the tubular conduit and a main valve secured to the upper end of the section of tubing operable to introduce reagents into said magazine through a passage in said main valve, a fluid injecting pipe terminating in a discharge port into said connecting section of tubing below said main valve, a pressure regulating valve in said injection pipe for admitting iiuid under pressure through said injecting pipe and a pressure gage operably connected in said pipe between said regulating valve and said discharge port, whereby a charge of reagent may be passed by gravity through said open main valve into said charging magazine and, upon first closing said main valve and thereafter opening said pressure regulating valve and said flow controlling valve in said tubular conduit, said charge of reagent may be projected downwardly into said tubular conduit for dissolving obstructing incrustations therein.

2. In a producing well having an assembly of equipment including a christmas tree for maintaining the well under pressure, a tubular conduit extending into the Well and above the casing head and having a ow controlling valve intermediate its length and positioned above the casing head, an improved attachment which is secured to the upper end of the 4tubular conduit for the introduction of reagents into the well, While maintaining well production during treatment, said device comprising a section of tubing operably connected with said tubular conduit and providing a holding magazine for a charge ci a reagent, a pressure regulating valve and a screw operated charge support on the upper end of said section of tubing for releasably supporting a container containing a charge of .reagent in said magazine, whereby by turning said charge support in one direction said container is released and opening said regulating valve to introduce fluid pressure into the magazine, a charge of solvent may be forcibly projected into said Well casing for eliminating obstructing incrustations within said Well casing.

C. KENNETH EILERTS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 20,548 Otis Nov. 2, 1937 1,090,673 Beecher Mar. 17, 1914 1,817,201 Minor Aug. 4, 1931 1,849,190 Jackson Mar. 15, 1932 l,873,084 Walker Aug. 23, 1932 2,202,192 Cypher May 28, 1940 2,228,629 Jerrell Jan. 14, 1941 2,261,440 Layne Nov. 4, 1941 2,336,977 Bean et al Dec. 14, 1943 2,352,805 Scheuermann et al. July 4, 1944 2,411,044 Landrum et al Nov. 12, 1946 2,482,455 Bailey Sept. 20, 1949 

1. IN A PRODUCING WELL HAVING AN ASSEMBLY OF EQUIPMENT INCLUDING A CHRISTMAS TREE FOR MAINTAINING THE WELL UNDER PRESSURE, A TUBULAR CONDUIT EXTENDING INTO THE WELL AND ABOVE THE CASING HEAD AND HAVING A FLOW CONTROLLING VALUE INTERMEDIATE ITS LENGTH AND POSITIONED ABOVE THE CASING HEAD, A DEVICE SECURED TO THE UPPER END OF THE TUBULAR CONDUIT FOR THE INTRODUCTION OF REAGENTS INTO THE WELL, WHILE MAINTAINING WELL PRODUCTION DURING TREATMENT, SAID DEVICE COMPRISING A CONNECTING SECTION OF TUBING WHICH FORMS A CHARGING MAGAZINE FOR A REAGENT SECURED TO THE UPPER END OF THE TUBULAR CONDUIT AND A MAIN VALVE SECURED TO THE UPPER END OF THE SECTION OF TUBING OPERABLE TO INTRODUCE REAGENTS INTO SAID MAGAZINE THROUGH A PASSAGE IN SAID MAIN VALVE, A FLUID INJECTING PIPE TERMINATING IN A DISCHARGE PORT INTO SAID CONNECTING SECTION OF TUBING BELOW SAID MAIN VALUE, A PRESSURE REGULATING VALVE. 